


If my brother is Kira, who will do my homework?

by ItsaStorky



Category: Death Note (Anime & Manga)
Genre: Angst, Eight balls says:, Gen, Good Sibling Yagami Sayu, Good sibling Yagami Light?, How Do I Tag, Mind Games, My First Fanfic, Other Additional Tags to Be Added, Psychological Torture, Sayu - centric, ask again later, no beta we die like everyone else in the anime/manga
Language: English
Status: In-Progress
Published: 2020-09-17
Updated: 2020-09-24
Packaged: 2021-03-08 02:15:04
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 2
Words: 2,173
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26518066
Author URL: https://archiveofourown.org/users/ItsaStorky/pseuds/ItsaStorky
Summary: Sayu investigates her brother's strange behavior, and quickly wishes she hadn't.(Basically a story rewrite where Sayu becomes an unwitting player/pawn in the epic smack down between God and a nonbeliever)Tentative updates on Thursdays.
Relationships: L & Yagami Light, L & Yagami Sayu, Ryuk & Yagami Light, Ryuk & Yagami Sayu, Yagami Light & Yagami Sayu
Comments: 6
Kudos: 45





	1. Prologue

Then.  _ I could have walked away. _

Now. Toes barely reaching the floor of a cell that was falling further from the surface by the second, Sayu could only hang on tighter to the loop closing around her neck. It was inevitable, wasn’t it? These dreadful choking gasps, from the moment she had decided to open that door just to make  _ sure.  _

Then.  _ I could have stopped at his bookcase, or his closet, or his nightstand. _

Now. She was going to die, she was going to die, it had been written.  _ It had been written, _ it seemed from the very first chapter.

Then.  _ When I saw the fake bottom, the little hole beneath the drawer, I could have looked the other way and lived the lie I was supposed to be safely wrapped in. _

She wasn’t the sort of sister to go snooping; he wasn’t the sort of brother to keep secrets. He was a perfect, hard-working genius who had nothing to hide, and she was his perfect, supportive, younger sibling who could never doubt him. That was how it worked, those were the unspoken rights and rules of their perfect family.

_ I could have uncovered at that stupid little book, written in that stupid language I barely knew, and thought better. _

It had felt too much like an exciting, super-secret spy mission: to find out whatever made Light Yagami, certified golden child, spend all night locked in his room. It wasn’t  _ studying,  _ nobody needed to study that much, especially not her brother.

_ Death Note, it had sounded like some macabre joke, so unlike my brother. _

There had been more English on the inner cover, enough that Sayu couldn’t keep from groaning. She should have walked away. This couldn’t be why her brother had been withdrawing, why his gaze always seemed so far away at dinner, why she so often had to ask a homework question twice before he heard her.

_ The person whose name is written in this notebook will die. _

She could have stopped reading. It was ridiculous. This was not why she had heard her brother cry out in fear in an empty room.

_ This note  _ _ will not take effect unless the writer has the person's face in their mind when writing his/her name. Therefore, people sharing the same name will not be affected. _

This is not why she sometimes heard manic giggling when he thought no one was listening.

_ If the cause of death is written within the next 40 seconds of writing the person's name, it will happen. _

This was not why he had come home sweating, panting, and pale. The look behind his eyes empty but for bullet-shattered glass. Refusing her questions, wearily making his way upstairs and away.

_ If a cause of death is not specified, the person will die of a heart attack. _

Something in that sentence rang a bell at the back of Sayu’s head. With a furrowed brow, she turned from the inner cover to her brother's impeccable handwriting on the crisp pages.

_ Kurou Otoharada _

_ Takuo Shibuimaru  _ (written many times over in different variations) _ , traffic accident. _

_ Murayama Kiroshi _

_ Sazama Tamotsu _

She flipped the page, more names. Many familiar names. All violent criminals. All dead within the last two weeks. All killed by a heart attack (or Kira, if you believed the growing rumors).

_ What is this? What the hell is this? _

There had to be some sane justification. Saner than… whatever crazed half-baked conspiracy was being whispered at the back of her mind. Maybe her brother suspected something about the heart attacks, and wanted documentation. That was all.

That was it.

Sayu could have walked away, she could have willfully forgotten ever seeing that book. Instead she stood silent and still, flipping through the pages until they ended, and then flipped back again, as if they could offer the explanation she so desperately wanted to hear.

Now. There was no explanation, no excuse, no lie, no light, no place to rest. The only certainty left was her name.

Then. She only stopped when she heard  _ its  _ voice _. _ Gravelly, surprised, sinisterly amused.

**“Oh... this is just getting better and better.”**

Sayu whipped around, a yelp already tearing itself from her lips, quickly turning into a scream.


	2. My brother's shitty roommate

**Summary for the Chapter:**

> Ryuk enters stage left.

**“I would be careful with that.”** The shinigami drawled.  **“Wouldn’t want to break anything.”**

The violently shivering daughter of the Yagami household gave no indication that she had heard him, other than trying to melt further into the corner between the dresser and the wall. Her grip on her brother’s desk lamp did not falter, brandishing it out like a weapon.

At least, Ryuk supposed, she had stopped screaming. Although that may have been because she had forgotten how to breath properly. Her inhalations were too shallow, and too quick. He again had to wonder at the purpose of a Shinigami, when humans could so easily botch the simplest prerequisites of living.

**“Your name’s Sayu, isn’t it?”**

The girl sort of… squeaked, at the sound of her name, and Ryuk tried to hold in a chuckle. Then, remembering that he didn’t actually care, he laughed.

**“I’m not here to kill you, brat.”** He paused. **“Or uh, steal your soul, if that’s what you’re worried about.”**

He leaned down a little, just to watch her squirm. Here, finally, was a human who knew how to act around an entity of demise.

**“And sorry to disappoint ya, you’re not going to kill a shinigami with a lamp. So put it down.”**

After a few moments, her arm gave a final tremble, then dropped from exhaustion, though she still cradled the lamp close to her chest. Apparently satisfied, Ryuk rose, snatched a controller, powered up the nintendo 64 and crashed onto Light’s bed. He could wait.

Just as he was beginning to wonder whether it would be worth going to check if the Yagami mother had restocked the fruit basket (he doubted the girl would have the strength to run away so soon) he heard a voice like a chattering mouse.

“Sh... shini… shinigami?”

**“That's right. Shinigami, like a god of death. Still not going to kill you.”**

“Then… wh-why are you he-here? And..if… if you aren't going to ki-kill me, what  _ are  _ you going to do? To me?”

The death god placed one monstrously long nail to his chin, as if seriously pondering her question.

**“Well I’m here… because cram school is** **_boring._ ** **”**

That did not seem to be the answer the girl expected. Confusion swam into eyes already wide with fear.

**“Honestly, you need to have an intervention with your brother about his study habits. It’s starting to become unnerving. Anyway! I figured I’d skip today, and try to finally finish Peach’s Castle. But alas, you were already here. As for what I’m going to do to you...”**

Ryuk turned to give her a full view of his sharp smile.

**“Nothing. I just want to see what** **_you_ ** **are going to do.”**

“What…  _ I’m _ going to do?”

**“Yep. So get along. Do it. Your brother didn’t take so long.”**

“My brother…? What does my brother have to do with… any of this?”

If the embodiment of destruction could have frowned, he would have.

**“It’s obvious isn’t it? What with me, and my old death note.”** He pointed to where she had dropped the book in her fright. **“Despite your brother’s impressive attempts, you found it and presumably read it. So what are you going to do now?”**

Sayu’s eyes trailed over open pages filled in Light’s neat scrawl.

“You mean… that notebook was yours? It was the instrument of a shinigami? And those rules, those names… those deaths…” Her voice was dry. “Real?”

**“A bit slower on the uptake. But yes.”**

“And… and you’ve been making him write in it?” Ah. That might be the likely conclusion of an adoring sibling. Still, the eldritch horror scoffed.

**“Sure. If that’s what you want to believe.”**

There was a pause. When she spoke again, there was a tinge of anger in the younger Yagami’s tone. In the corner of his eyes, Ryuk could see her struggling to her feet.

“What is that supposed to mean?”

He shook his finger at the kid.

**“Nuh uh. You’re not going to get anymore hints out of me today squirt. I thought you would have figured it out, but since you haven’t, these lips are sealed. Well… in a manner of speaking anyway.”**

He reached to pick up the controller again, but was startled when quite suddenly Sayu’s hand was there first. She was staring at him. The faint glow of the waning moon seemed brighter when reflected in the white of her eyes, which were wide and wet. With fear? No, that wasn’t the right word anymore. She was hyperventilating again, but more quietly. And her grip on the controller was firm.

“You’re lying. You’re wrong. My brother...” She swallowed. “Light wouldn’t write those names. He would  _ never kill all those people _ . Not willingly.”

Ryuk almost felt bad for her. Really. But clearly the eldest sibling had inherited all the critical thinking.

**“As I said. Believe what you want to believe.”**

In the wake of his words. Her scrutiny felt strangely heavy. She seemed to search every fold, every crease of his gruesome expression, although Ryuk could not imagine to what end. A Shinigami’s face did not contort with or betray emotional insight. Still, when she finally turned away, nails digging into her palms before she leaned down to pick the book off the floor, opening it again to its first page. He had to wonder what she found.

“Oh my god.” She whispered finally. “This can’t be happening.”

_ I’m afraid “god”, yours or otherwise, would disagree, brat. _

“This  _ really can’t _ be happening. I’ve seriously just had a psychotic break from reality.” She sunk back to the floor with a snicker. “First failing chemistry and now this. Dad’s gonna be so disappointed.”

She gave Ryuk a wry smile.

“And Mom, should I even tell her? She’ll be going to those housewife get-togethers, and all the other moms will be saying ‘My Sasuko got first in track.’ ‘My Tanaki got an A in maths.’ and my mom will have to go ‘My kid’s crazy, talks to death gods if you’ll believe it.’ Haha. And Light…”

She drifted off after that. The ghoulish demon was unimpressed.

**“Look, uh, if all you’re going to do is sit on the floor of your brother’s bedroom and mope until he or your parents find you here. Mind if I go get him now and speed things up a little? I’m sure he’ll happily skip cram school if he hears he has to come take care of his poor little sister.”**

_ And after all the work he put in to make sure he wouldn’t have to. What a shame. _

Sayu frowned at the way he purred the last few words, her eyes having lost the light of the moon, becoming more akin to orbs of opaque glass. Surprisingly though, her lips pressed into a straighter line.

“I guess I should clean up before he gets back. Whatever the case, I don’t want him knowing I went through his stuff.”

And off she went. Putting the lamp back on the desk, straightening the carpet, making sure the books were in the right order. Then she was cautiously returning the death note to where she found it, using a single-use chopstick to hold the fake bottom up.

**“You aren’t going to take it? Not even a page?”** Ryuk didn’t bother hiding his curiosity.

Sayu looked at him with what seemed genuine confusion. “Why would I do that?” But the Shinigami didn’t respond, only continued observing her with eyes unblinking.

Apparently deciding the room looked relatively undisturbed (other than the Shinigami playing video games on her brother’s bed) Sayu turned to leave, but paused at the door.

“Are you going to stay here?” She asked.

**“Yup. I usually follow Light around though, so I won’t be here all the time. You’ll see me at family mealtimes I guess. Think of me as your secret 5th housemate! Oh, and if you’re gonna stick around you should probably know, only those who have touched the death note can see me.”**

“Oh.” Sayu responded dully. “Are you going to tell my brother I was in his room?”

**“Nah. I’m not on his side or anyone else’s. Just want to watch what happens. So I’m serious, no more freebies.” At this he turned to look at the girl head on, considering. “Well… not without a price anyway.”**

The girl tried to think of how to respond. 

“Ok. See you around I guess.” 

She turned, locked the door, and only just remembered to slide in the slip of paper before she closed it behind her. Disappearing to do whatever human’s did when they found out their brother was a mass murderer, Ryuk supposed. Or were in denial over such a fact.

_ Humans are so interesting.  _ The unholy monstrosity pondered.  _ I wonder how this will all go down. _

**Notes for the Chapter:**

> Uhhhh I hope I did a good job portraying our favorite nihilistic death god.
> 
> Also, I was reading the manga again and realized I got the timeline messed up, as you do. So for clarification, in this AU Light set's up his notebook hiding spot BEFORE the first confrontation with L. Ryuk managed to tell him about the touch notebook-see shinigami rule earlier I guess.
> 
> Bonus?: https://thoughtlesssadness.tumblr.com/

**Author's Note:**

> If people seem to like this, I'll try to continue, but don't count on it lol.
> 
> Critique and advice is appreciated.
> 
> I do not own Death Note, or any of it's characters.


End file.
